Method and apparatus for projecting comminuted materials



Dec. 15, 1931. H. A. MULVANY METHOD AND APPARATUS FOR PROJECTING COMMINUTED MATERIALS Filed Npv. 16, 1927 2 Sheets-Sheet INVENTOR.

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Dec. 15, 1931. H. A; MULVANY 4 72 METHOD AND APPARATUS FOR PROJECTING COMMINUTED MATERIALS Filed Nov. 16, 1927 '2 Sheets-Sheet 2 INVENTOR.

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Patented Dec. 15, 1931 PATENT OFFICE HARRY A. MULVAN Y, OF BERKELEY, CALIFORNIA METHOD AND APPARATUS FOR PROJECTTN'G OOMIU'NUTED MATERIALS Application filed November 16, 1927. Serial No. 233,726.

This invention relates to a method and apparatus for projecting comminuted materials such as sand, ground abrasive materials, etc.

Sand and other materials are extensively employed as abrasives for cleaning the stone facing of buildings; in the metal arts for cleaning or smoothing metal castings and other metal objects; in the glass and other industries for imparting a dull surface to 1 numerous articles; and more recently its use has also been applied to food products, such as the dry cleaning of eggs by a sand blast. In any instance, the cleaning, smoothing or dulling efi'ect obtained is due to the abrasive action of the sand or other material employed, and the result obtained is caused either by projecting the abrasive with high velocity against the object to be treated, as by an air blast, or by forcibly rubbing the abrasive against the surface to be treated.

The most common method employed is the sand blast method. This, however, has numerous objections such as large, costly'and cumbersome apparatus which requires trained and skilled operators, the horsepower consumed per square foot of area treated is excessive (the air friction and back pressure accounting for a large part of the power loss), atmospheric conditions in the immediate vicinity are not desirable due to the dust liberated, etc.

The object of the present invention is to generally improve and simplify the sand blasting method by providing means for projecting the sand or other material employed at high velocity against an object to be treated by centrifugal or impelling action and without the use of air; and further to provide a novel form of conveyor whereby the objects to be treated may be supported and rotated while subjected to the abrasive action of the sand or other material. The apparatus employed is shown by way of illustration in the accompanying drawings in which:

Fig. 1 is a side elevation of the apparatus, said side elevation being shown partly in section,

Fig. 2 is an enlarged detail sectional view of the conveyor and the rollers supporting the same,

Fig. 3 is an enlarged cross-section of the conveyor, the rollers supporting the same and the guides whereby the objects to be treated are maintained on the conveyor,

Fig. 4 is an enlarged end view of the apparatus shown in Fig. 1,

Fig. 5 is an enlarged cross-section taken on line VV, Fig. 1.

Referring to the drawings in detail and particularly Figs. 1 and 5, A indicates a horizontally disposed frame supported at opposite ends by standards or uprights such as indicated at 2. J ournaled on the uprights of the frame are pulleys 3 and 4: and supported by the pulleys is a pair of endless conveyor cables 5 and 6 which will hereinafter be described. Disposed substantially centrally of terial but their faces are preferably covered with rubber and a corrugated finish is desirable as indicated at 11. These rollers rotate at a high speed and sand or a like material is delivered between the rollers in the direction of arrows at from one or more openings formed in the bottom port-ion 12 of a hopper 13. The rollers rotate in the direction of arrows b or towards each other and the sand is thus engaged by the corrugations or the surface of the rollers and as such is projected at high velocity downwardly between the rollers. The objects to be cleaned, for instance eggs or the like indicated at 15, are placed on the conveyors 5 and6 and as such aresubjected to the abrasive. action of the sand as it is projected against the eggs under high velocity. The sand-orother material employed after serving its purpose, collects on an inclined bottom section 14 formed in the housing B from where it is delivered to a lower chamber 15a. The sand is here picked up by the buckets 16 of an endless conveyor 17 and as such is redeposited in the hopper 13 for re-use. The upper end of the housing is connected through a pipe 17a with the suction side of a blower 18 and any dust which is formed is thus automatically and continuously carried away from the housing.

The endless conveyors 5 and 6 are best illustrated in Figs. 2 and 3 and as they are both identical in construction, the description of one will suflice. The conveyor consists of an endless steel cable 19. Surrounding the endless cable is a plurality of comparatively short sections of helical spring wire 20 and covering each helical section is a rubber sleeve or tube 21. Any number of sections may be employed so as to provide sufiicient resiliency when the conveyor is passing around the pulleys 3 and 4, and each section is separated by a washer or the like indicated at 22. The cable 19 serves two functions, first that of a support, and secondary, that of a bearing member, i. e., each helical spring 20 with its rubber covering 21 is rotated about the cable at the time that the eggs pass under the projected sand and for a short period thereafter as it is desirable to inspect the eggs after they leave the sander or in other words pass from under the rollers 86 and 9?) by which the sand is projected against the eggs. Another reason for rotating the eggs is to insure perfect cleaning of the entire surface, for instance if they should remain in a stationary position while resting on the conveyor and passing under the rollers 86 and 9?), only the top surface of each egg would be clean but if they are rotated about their longitudinal axes while subjected to the abrasive action of the sand, the entire surface will be cleaned. It is, accordingly, more or less essential to rotate the eggs several revolutions about their axes while the abrasive material is being projected thereon. The cable 19 as previously stated serves as a bearing and a support, while the helical springs 20 serve as hearing bushings and a support for the rubber sleeves or coverings 21, i. e., the spiral springs are comparatively free with relation to the cable and as such may rotate about the same. The eriod of rotation is only necessary while t e eggs pass under the rolls 8?) and 9b and for a short time thereafter and this rotation is imparted to each section during this period by means of a plurality of rollers generally indicated at 30, 31 and 32. These rollers are secured on shafts as shown in Fig. 3 and one end of each shaft is provided with a gear as shown at 33. These gears intermesh with the intermediate gears 34 and the outer most shaft is provided with a sprocket gear 35 (see Fig. 1) which is driven by a chain 36 from a driving sprocket 37. With this drive the rollers 30, 31 and 32 will rotate in the same direction as indicated by the arrows and the rubber sleeve sections 21 will also rotate in the same direction as indicated by the arrows but in a direction opposite to the rollers 30, 31 and 32; as the eggs or other objects to be sanded are supported by the conveyors 5 and 6 which are surrounded by the sectional rubber tube or sleeve sections 21 it is obvious that each egg will rotate in the direction of the arrow (see Fig 3), this being important as it insures a thorough cleaning of the entire egg surface. The rollers 30, 31 and 32 extend to the point indicated at 40 (see Fig. 1) and the eggs may thus be thoroughly inspected before they are removed from the machine. The sprocket 37 is secured on a shaft 41. This is driven through a suitable gear reduction 42 which in turn is driven by a motor 43. This motor is also provided with a belt drive 44 and motion is thus imparted to the conveyor members 5 and 6 as the belt drives a pulley 4a which cooperates with the pulley 4. The shaft 41 extends completely through the housing and as such also forms the drive shaft of the elevator 17 shown in Fig. 5. There are three driving motors employed, the motor shown at 43 serving the function of driving the endless conveyors 5 and 6, the sand elevator 17, and the rollers 30, 31 and32, as these are driven from the shaft 41 through the sprocket chain drive indicated at 36. The other motors are indicated at 8a and 9a. These are directly coupled to the shafts 8 and 9 and the shafts and sand projecting rollers are thus driven independently of any other driving mechanism so that a high speed may be insured and the proper velocity transmitted to the sand or other abrasive employed. The eggs or other objects to be cleaned are placed on the conveyors at the point indicated at in any suitable manner. They are sanded while passing under the rollers 8 and 9, and, as previously stated, rotated about their longitudinal axes during this pe riod and they continue to rotate until they reach the point 40, being thereafter removed at the point in any suitable manner. Guide bars such as shown at extend from end to end of the housing so as to guide the eggs and prevent accidental removal while they are being subjected to the abrasive action of the sand, in fact these guide bars are preferably extended to the point 40 so that breakage of individual eggs by rolling oif the conveyor members 5 and 6 may be entirely avoided. This danger is entirely eliminated after rotation of the eggs stops and it is for this reason that the guide members terminate at the point 40. The pulleys 3 and 4 may be individual pulleys or they may be double-groove pulleys as shown at (see Fig. 4).

By constructing a sanding machine as described it is possible to project sand at practically any velocity desired without the use of an air blast or the like. This is desirable as it reduces dust conditions; it reduces the horse-power required per square foot of area treated or cleaned; it simplifies the mechanism and materially reduces the size and space occupied. The mechanism is simple and skilled operators can accordingly be entirely dispensed with.

While certain features of the present invention are more or less specifically described, I

(wish it understood that various changes may be resorted to within the scope of the appended claims; similarly, that the materials and finishes of the several parts employed may be such as the manufacturer may decide or varying conditions or uses may demand. 1

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. An apparatus for projecting a coin minuted material, comprising a pan of parallelly arranged elongated interspaced rollers, said rollers presentinga corrugated resilient surface with the corrugations running longitudinally of the rollers and the corrugations being shallow, means for rotating the rolls at a high speed in directions opposite to each other so that the surface of the rolls will move towards each other nuted material comprising apair of parallellyarranged closely spaced rotors, closely spaced resilient pro ections formed on the surface of each roller and extending from end to end thereof, means for rotating the rotors at a high speed in a direction towards each other on one side, and means for delivering the comminuted material to be protats away from each other, and means whereby objects to be treated will be moved through the area where the comminuted material is being projected under high velocity.

I HARRY A. -MULVANY.

jected at a point between the rotors where it will be engaged by the projections on both rotors and projected at a point where the rotors rotate away from each other.

3. An apparatus for projecting comminuted material comprising a pair of parallelly arranged .closely spaced rotors, closely spaced resilient projections formed on the surface of each roller and extending from end to end thereof said projections being radial and projecting only a short distance from the surface of the rollers, means for rotating the rotors at a high speed in a direction towards each other on one side, the comminuted material to be projected at a point between the rotors where it will be engaged by the projections on both rotors andpro ected at a point where the rotors romeansfor delivering 

